1. Field of the Invention
The present invention relates to a sealing lip assembly for sealing the underwater or bottom side of centerboard or variable keel fin systems on surfboards and sailboats.
2. Description of the Prior Art
Various seals are used today for sealing the underwater or bottom side of centerboard systems on surfboards and sailboats, but they do not completely fulfil their function of closing the opening in the centerboard case in a flow-tight and non-vortical manner in every position of the centerboard.
These seals are made, for example, of rubber, plasticized PVC or sailcloth which is screwed or glued to the surfboard or sailboat by the aid of thin ledges. The advantage of these materials is that the centerboard can be pressed out of the centerboard case without great expenditure of energy because the resistance against being bent up is small. However, during sailing or surfing the small resistance allows for the sealing lips to be pressed in undesirably or, when the oncoming flow is lateral, to be raised up in the slack area, giving rise to vortices on the bottom of the boat or board. When the centerboard is pivoted into the centerboard case, the sealing lips are increasingly drawn into the centerboard case at the rear and cannot form a continuous transition from the bottom of the boat or board to the centerboard.
Soft rubber or synthetic seals are glued to the surfboard but are often detached and tear during surfing. Furthermore, the known seals cannot be adapted without any transition to the shape of the sliding bottom in mass production.
For these reasons, sealing lips are dispensed with today in many surfboards having fully lowerable centerboard systems, the centerboard case being profiled so as to be as favorable to flow as possible.